textproduct: Albany

WHAT HAS CHANGED

There is also a low to moderate chance for isolated to scattered snow squalls tomorrow afternoon and we have added slight chance to chance for brief periods of heavy snow showers tomorrow morning into the afternoon. The highest chance for snow squalls looks to be mainly along and north/west of I-90.

Guidance has come into better agreement on the winter storm track for Sunday into Monday and the latest probabilistic guidance for amounts 7 inches or higher have increased to 50 to 70% across much of eastern NY and western New England. A south to north snowfall gradient expected.

KEY MESSAGES

1) There is a medium chance for isolated to scattered snow squalls tomorrow morning into the afternoon which can result in slippery travel and brief reductions to visibility. The highest chances are from the Capital District north and west.

2) High confidence for dangerous cold Friday night through Saturday resulting in an increased risk for hypothermia and frostbite.

3) Increasing confidence for at least moderate impacts from a winter storm Sunday into Monday, especially along and south of I-90.

DISCUSSION

KEY MESSAGE 1...

Isentropic lift ahead of a clipper tracking through Canada continues to increase this afternoon with bands of snow already underway in west/central NY which are tracking north and west. Expecting snow to spread in the southwest Adirondacks, Mohawk Valley, Upper Hudson Valley, southern VT and even parts of the Capital District this afternoon. As southwest winds within the incoming low and mid jet become directed along the south facing slopes of the southwest Adirondacks and along the spine of the southern Greens through this evening, snowfall rates will likely become moderate to even heavy reaching 0.5 - 1.5 inches per hour as shown in the latest HREF guidance. Snowfall rates weaken after Midnight as winds in the low and mid level jet veer to the west with moisture lifting out of the region as we enter into the respective warm sector. Temperatures tonight should follow a non-diruanl trend with lowest temperatures occurring this evening before temperatures gradually warm towards morning. Overall, expecting 4 to 8 inches along the south facing slopes of the southern Adirondacks through 12 UTC Thursday with 2 to 5 in the southern Greens. Coating to 1 inches expected for areas along and north of I-90 with 2 to 4 inches along the foothill of the southern Adirondacks.

The associated cold front then slides towards eastern NY rather early tomorrow with forecast soundings showing steepening lapse rates ahead of the boundary generating weak low-level instability. There is now growing confidence in isolated to scattered snow squalls tracking south and east into the southern Adirondacks, Upper Hudson, and Mohawk Valley by 12 - 15 UTC before tracking into the Greater Capital District by 15 - 18 UTC. Despite these heavy snow showers/squalls arriving rather early in the day, the favorable ingredients for snow squall seem to be in play with the snow squall parameter highlight areas mainly along and north of I-90 through 18 UTC lining up with the better upper level forcing. Snow showers/squalls look to weaken as they track south and east of Albany tomorrow afternoon as they outrun the best forcing. Winds shift to the west and northwest during any snow shower/squall with incoming cold air advection deepening the mixed layer winds and supporting gusty winds reaching 30 to 40mph. While temperatures ahead of the snow showers/squalls peak into the mid to upper 30s and then dropping below freezing, ground temperatures will likely already be below freezing given the recent cold so a flash freeze is unlikely. Even still, brief burst of moderate to heavy snow combined with the gusty winds can result in reduced visibility during any snow squalls and more hazardous travel.

KEY MESSAGE 2...

High confidence that the coldest temperatures of the winter so far will sweep into the Northeast Friday into this weekend resulting in an increased risk for hypothermia and frostbite. Initially on Friday, the main trough and arctic front responsible for the incoming frigid temperatures will actual be to our west as an impressive 1050 hPa high builds into the Upper Plains. This will mean that while Friday starts off chilly, the true arctic air mass will still be to our west and we actually rise into the low to mid 20s (even near 30 in the mid- Hudson Valley) through early afternoon before the main trough axis and arctic front swings through closer to 18 - 00 UTC. Additional snow showers may develop along or right ahead of the boundary but overall moisture is even more limited so limited POP to chance and slight chance for areas from the Capital District north and west. Behind the arctic front, westerly winds shift to the northwest winds and while winds will already be breezy, they were will turn even stronger as the bitterly cold air mass surges eastward and the mixed layer deepens.

Impressively, the 925 - 850 hPa isotherms ranging from -25C to -30c plunge into the Northeast Friday night and combined with the continued strong northwest winds 30 to 40mph overnight will lead to dangerous wind chills. Latest probabilistic guidance shows 50 to 80% chance for Friday night temperatures to plummet below 0 for much of eastern NY and western New England (except in the mid-Hudson Valley where the chance is less than 25%). In fact, there is a 30 to 60% chance that the southern Adirondacks drop below -20F! Needless to say, the combination of such cold temperatures and continued strong winds will support an increased risk for hypothermia and frostbite as wind chills or the "feel-like" temperatures drop to -15F to -30F. Given the high confidence, extreme cold watches have been issued for the southwest Adirondacks and southern Greens from 00 UTC to 18 UTC Sat where confidence in reaching -30F wind chills is highest. Cold weather advisories will likely be needed across much of the rest of the region. Bottom line, stay indoors Friday night and avoid any unnecessary exposure to the outdoors.

Northwest winds remain breezy Saturday morning supporting continued dangerous wind chills so continued to avoid unnecessary time outside. Our 1045 hPa high slides into the Midwest/Great Lakes by the afternoon, maintaining the northwest wind trajectory and cold air advection regime but weakening the sfc pressure gradient and allowing winds to gradually weaken. Even though wind chills will not be quite as cold as Friday night or Saturday morning, the heart of our arctic air mass will be overhead and temperatures will struggle to warm. In fact, there is high confidence (greater than 70% chance) that temperatures will remain below 10 degrees. Despite the weakening winds, even a light wind alongside such frigid temperatures will result in dangerous wind chills and cold weather advisories may be needed even during the day, especially for the higher terrain/hill towns. Winds turn even lighter by Saturday night as the high moves overhead and while wind chills will be less of a concern, very cold temperatures are likely. There is once again a 50 to 80% chance that lows fall below 0 again (less than 20% chance mid-Hudson Valley) but wind chills will not be as concerning as Friday night.

Besides dangerous cold, yet another lake effect snow band will likely develop off Lake Ontario and be directed into northern Herkimer and Hamilton County Thursday afternoon into Friday afternoon. Impressive lake-induced instability looks to reach the extreme classification given the arctic cold blast over the Lake Ontario waters, likely support high snowfall rates in excess of 1" per hour Thursday night into Friday morning. However, these extreme instability cases tend to limit the eastward extend so less confidence that the high snowfall rates extend into Hamilton County. While the initial flow will direct the band mainly north of Old Forge Thurs P.M/evening, the mean layer flow veers to the west overnight into Friday morning, allowing the band to slide southward closer to Route 28 and Old Forge. Once the main arctic front tracks into the southwest Adirondacks late Friday afternoon or early evening, the main band will become disrupted and weaken but still slide southeastward into the Mohawk Valley, bringing light snow accumulations.

KEY MESSAGE 3...

The latest ensemble and deterministic guidance has come into better agreement and there is growing confidence that eastern NY and western New England will see at least moderate impacts from a winter storm Sunday into Monday. While there is high confidence in a winter storm impacting the Southeast U.S with winter storm watches already in effect, there was uncertainty regarding how the storm would track once it reached the East Coast. The main reason for this uncertainty stemmed from an upper level trough digging out of the Canadian Prairies into the Rockies and if and when it would phase with an additional southern stream shortwave ejecting out of the Desert Southwest. The latest ensemble clusters continue to show two potential solutions. The first suggests that phasing does take place, amplifying downstream riding off the East Coast just in time for the winter storm to track north/west closer to the NJ/Long Island coast Sunday into Monday. The other solution suggests the trough actually remains weaker and therefore does not phase. This would maintain a more zonal flow pattern across the Eastern CONUS which would allow our winter storm to escape to our south/east. While these two scenarios are still on the table, there is more agreement in the first scenario occurring which increases confidence in at least moderate winter storm impacts for eastern NY and western New England. However, the devil is in the details and there remain disagreements on the exact timing and placement of the phasing which will impact when we can expect the worst impacts and placement of any snow bands.

It is worth noting that while this storm is still four days away, there is rather good agreement among the guidance on the overall storm track which givens us increased confidence to message at least moderate impacts at this lead time. The Probabilistic WSSI from WPC highlights 60 to 80% chance for moderate impacts or hazardous travel conditions across areas from I-90 southward with even a 60% chance for major impacts or considerable disruptions closer to the I-84 corridor Sunday into Monday. Given the storm track now favors crossing near the 40N/70W benchmark, such a track supports a south to north snowfall gradient with the highest amounts south of I-90. In fact, the latest probabilistic guidance shows 50 to 70% chance for at least 7 inches of snow (winter storm warning criteria) focused there. If you have plans to be on the road Sunday or Monday, consider making alternative plans as there is growing confidence in this storm resulting in hazardous travel. Luckily, the frigid temperatures that will still be place ahead of and during this storm will likely keep our precipitation type as all snow and support higher than normal SLRs or a light/fluffy snow type.

AVIATION /00Z THURSDAY THROUGH MONDAY/

Flying conditions are currently VFR for all sites with bkn-ovc cigs around 4-6 kft. Ahead of an approaching clipper system, southerly winds are in place across the region. While sheltered areas (such as KPOU and KGFL) are seeing lighter winds, the larger valley areas around KALB is allowing for gusty winds, with some gusts over 25 kts. These winds will continue through the evening hours. Some LLWS is possible for areas where surface winds stay light (such as near KPOU) as 2 kft winds will be 30-40 kts from the southwest.

As the clipper approaches, some scattered snow showers are possible around 04z-07z and again along a line from around 08z-12z. These will primarily impact KGFL and KALB, but KPSF may be close enough for impacts as well. Based on hires guidance, KPOU should be far enough south to avoid this activity. Within snow showers, visibility will be reduced to IFR levels, with visibility 1-2SM and ceilings lowering to 1500-3000 ft. Have included TEMPOS and PROB30 to account for these possible passing snow showers.

After daybreak, the storm's cold front will be passing through, allowing winds to become southwest for Thursday morning and eventually westerly by Thursday afternoon. Winds will be increasing, especially by afternoon, when some gusts will be over 25 kts again (mainly for KALB). With the upper level shortwave overhead, some additional passing snow showers and squalls can't be ruled out around midday Thursday, but this activity will be fairly scattered in coverage. Still, any snow showers will be capable of a brief reduction in visibility and ceiling. Skies will be clearing out by late Thursday, with VFR conditions.

Outlook...

Thursday Night: No Operational Impact. NO SIG WX. Friday: Moderate Operational Impact. Windy With Gusts To 30 kts. Slight Chance of SHSN. Friday Night: Low Operational Impact. Breezy. NO SIG WX. Saturday: No Operational Impact. NO SIG WX. Saturday Night: Low Operational Impact. Slight Chance of SN. Sunday: High Operational Impact. Likely SN. Sunday Night: High Operational Impact. Likely SN. Monday: Moderate Operational Impact. Chance of SN.

CLIMATE

January 24

Record Cold High Temperatures:

Albany, NY: -1 degrees set in 1882 Glens Falls, NY: 0 degrees set in 1907 Poughkeepsie, NY: 8 degrees set in 1948

Record Cold Low Temperatures:

Albany, NY: -17 degrees set in 1948 Glens Falls, NY: -30 degrees set in 2011 Poughkeepsie, NY: -15 degrees set in 1961

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...Winter Weather Advisory until 1 PM EST Thursday for NYZ032-033- 082. Extreme Cold Watch from Friday evening through Saturday afternoon for NYZ032-033-042-082. MA...None. VT...Extreme Cold Watch from Friday evening through Saturday afternoon for VTZ013-014.